The development of tumor often involves a chromosomal rearrangement such as translocation resulting in altered gene regulation and expression. For example, thyroid adenoma is a tumor showing clonal chromosomal abnormalities with trisomy 7 and chrosmosomal rearrangements. Thyroid adenomas are highly frequent human tumors that can be distinguished from their malignant counterparts, i.e. follicular carcinomas by an encapsulated growth and a lack of invasiveness, respectively. Even in iodine sufficient areas thyroid adenomas occur in 4-7% of adults and in iodine deficient areas this number can rise to about 50%. The pathogenesis of these frequent benign tumors is only poorly understood but clonal chromosomal aberrations can be observed in roughly 40% of the nodules and are likely to pinpoint genomic regions and genes relevant for the development of the disease (DeLellis, Pathology and genetics of tumours of endocrine organs, editorial and consensus conference in Lyon, France, Apr. 23-26, 2003, 320 S. IARC Press, Lyon, 2004). Roughly 20% of the tumors show clonal chromosomal abnormalities with trisomy 7 (Bartnitzke et al., Cancer Genet. Cytogenet. 39 (1989), 65-68) and about 20% of the tumors with clonal cytogenetic aberrations show abnormalities involving chromosomal band 19q13 (Belge et al., Cancer Genet. Cytogenet. 101 (1998), 42-48). Given the extremely high prevalence of thyroid adenomas in Europe and the U.S. alone four to five million people can be estimated to be affected by this genomic alteration in their thyroid. The 19q13 breakpoint has been assigned to a segment of 150 kb by positional cloning and possible target genes in that cluster region have been investigated in some detail (Beige et al., Cytogenet. Cell Genet. 93, (2001), 48-51; Rippe, et al., Genes Chromosomes Cancer 26 (1999), 229-236). However, the long arm of chromosome 19 shows an extraordinary high gene density compared to other regions of the human genome, and so far only protein-encoding genes have been considered as targets of these highly frequent structural chromosome abnormalities.
In spite of considerable research into therapies for tumor involving chromosomal aberrations, this type of tumor and in particular thyroid adenoma remains difficult to diagnose and treat effectively, and indicates that improvements are needed in the diagnosis, treatment and prevention of the disease.